Hydraulic torque transmission arrangement



Feb. 27, 1945.

J. H. DORAN HYDRAULIC TORQUE TRANSMISSION ARRANGEMENT Filed Feb. 20, 1942 Inventor:- John H. Doran,

l-Iis Att'orn e y.

Patented Feb. 27, 1945 Jan-n. Doran, Scotia, N. Y., asaignor to General Electric Company, a corporation of New York Application February 20, 1942, Serial No. 431,742

The present invention relates to hydraulic torque transmission arrangements, particularly to the kind of arrangements which at times are to operate'as hydraulic couplings and at other times as hydraulic torque converters. The invention is of particular interest in connection with vehicles, tools and like machinery in which torque is to be transmitted from a drive shaft to a driven shaft.

The object of my invention is to provide an improved construction of hydraulic torque transmission arrangements whlch is simple in design and may be operated at relatively high efllciency within a wide range of torque and speed.

For a consideration of what I believe to be.

novel and my invention, attention is directed to the following description and the claim appended thereto in connection with the accompanying drawing.

In the drawing Fig. 1 ilustrates a torque transmission arrangement embodying my invention; Fig. 2 is a section along line 2-2 of Fig. 1; Fig. 3 is an enlarged detail view of apart of Fig. 1; Fig. 4 illustrates a part of Fig. 1 in a difierent operating position, and Fig. 5 is a modification according to my invention.

The transmission according to my invention broadly includes a pump preferably of the positive displacement type connected to a drive shaft for supplying fluid under pressure to a plurality of parallel-connected hydraulic motors, preferably of the positive displacement type, and having elements connected to a driven shaft. The arrangement includes valve mechanisms for automatically connecting and disconnecting some of the motors in response to changes of an operating condition together with valve means for reversing the direction of rotation of the motors. In the arrangement illustrated inthe drawing I have shown a hydraulic pump ill of the positive displacement type, in the present instance a gear pump (Fig. 2) having two gears I hand l2 meshing with each other and supported on shafts l3 and respectively. The gears are enclosed within a casing 15 having an inlet conduit l6 and an outlet ll for operating fluid. O'ne The discharge conduit ll of the pump III is connected to a plurality .of hydraulic motors 20. In the present instance I have shown four such 1 Claim. (01. 60- 53) motors 2|, 22, 23 and 24. The construction of the motors is similar to the construction oif'thepump I ll. They form a unitary structure with a casing 25 and a driven shaft 26 to which one of two gears 21 of each motor is secured. Opposite casing portions of each motor have flrst and second openings or ports connected to conduits 28 and 29 forming inlets and outlets for operating fluid. In case the fluid is supplied through the conduit 26 the motors run in a certain direction of rotation and the fluid is discharged through the conduits 29. Vice-versa, if the fluid under pressure is supplied through the conduits 29 the motors run in the opposite direction of rotation and the conduits 26 form outlets for the operating fluid. The conduits 26 are connected to spaced. portions of a. control valve means 30 which comprises a cylinder 3i having w member 96 with a bottom portion integrally se'-' spaced portions connected to the conduits 29 and a piston or movable valve member 32 m0v'-' ably disposed within thecylinder 3!. Similarly; the conduits 29 are connected to a control valve means 33 comprising a cylinder having spaced portions connected to the conduits 29 and a movable valve member or piston 36 slidably disposed within the cylinder 34.

The piston 35, as shownmore clearly in Fig. 3, comprises a hollow piston member or cylindrical cured to a stem 31 and a'wall forming openings 38. The left-hand portionof 'the cylindrical ll secured to and broadly forming an extension of-the stem 31. In a certain position, as indicated in Fig. 3, the openings 38 register with the conduits 29 to permitthe discharge of fluid under pressurefrom the conduits "through the ports or openings 66 into the cylinder 34. Broadly the spring-biased'plate 99 constitutes a check or pressure relief valve for relieving fluid under pressure from the cylindrical member 36 whenever such member is in a position in which its ports 38 register with one of the cylinder ports to which a motor discharge conduit is connected.

-nism 39, whence the fluid flows through the shown in Fig. 1 the channel 49 connects the ports 44, 45 and the channel 50 connects the ports 45, 41. Upon clockwise turning of the valve member 43 into the position shown in Fig. 4, the channel 49 connects the ports 45. 45 and the channel 59 connects the ports 4|, 41.

The discharge conduit ll of the pump I is connected to the port 44 while the port 45 is connected by a. conduit through a heat exchanger or cooler 52 to the cylinder 34 01 the valve mech- 1 anism 33. The port 41 is connected by a conduit 53 and a branch 54 to the cylinder 3| of the valve mechanism 39. The control valve mechanisms 30 and 33 are automatically controlled in response to changes of certain operating conditions. To this end the stems 31 of the mechanisms are connected to the ends of a lever 55 which has a central portion secured to a stem 55. The latter forms part of a hydraulic motor or pressure responsive device 51 having a cylinder 58 and a piston 59 movably disposed in the cylinder and secured to the righthand end of the stem 55. The piston 59 is biased towards the left by a compression spring 59 held between the piston 59 and a, spring plate 5| adiustably supported on a bolt 52. The piston 59 and the cylinder form a pressure chamber 53 connected by a conduit 54 with a restriction or reduced portion 55 to the aforementioned conduit 5| and by another conduit 55 with. a restriction or reduced portion 51 to the aforementioned conduit 53.

The operation of the mechanism is as follows: Assuming that the shaft |3 of the pump I9 is driven by a suitable power agency and the shaft 25 of the motors is connected to drive a'vehicle or Iike machine subject to varying load conditions, operating liquid then is conductedfrom the tank or reservoir l9 through the inlet conduit |5 to the pump l0 and discharged therefrom under pressure through the conduit II, the channel 49 of the reversing valve 42, the conduit 5| and the heat exchanger 52 to the cylinder 34 of the control valve mechanism 33. The operating fluid such as oil is conducted from the cylinder 34 through the conduits 29 which in this instance form inlet or supply conduits into the motors 2|, 22, Hand 24. Assuming that the gears of the motors 2| to 24 are stationary, as is the case during starting, a high pressure is built up in the Pressure chamber 53. Fluid under pressure is supplied to the latter from the conduit 5| through the conduit 64. The pressure in the chamber 53 forces the piston 59 towards theright thus moving the pistons 35 and 32 of the valve mechanisms 33 and 30 respectively into the righthand end positions, thus assuring that the inlet conduits 29 of all motors are connected to receive operating fluid from the cylinder 34. The fluid under pressure causes turning of the gears of the motors2| to 24 and accordingly of the output shaft no 25 and the machine connected thereto. The op. erating fluid is discharged from the motors through the conduits 28 which then form outlet conduits into the cylinder 3| of the valve mecha- M branch conduit54, the conduit 53 and the channel 59 of the reversing valve 42 through the port 45 into a drain conduit 59 connected to the reservoir ortank 8.

The operating fluid on its passage through the fluid circuit described above is cooled in the surface type heat exchanger 52.,. The movable valve members of the mechanisms 39 and 33 being rigidly secured to the lever 55 are always in the same relative positions with respect to each other.

In the position shown, the valve mechanisms permit the operation of all four motors ofthe unit 29, permitting the creation of high torque at relatively low speed which is important during starting of and sudden high load demand on the output shaft 25.

Upon starting and rotation of the gears of the motors 2| to 24 the resistance to flow of fluid through the motor decreases. Accordingly the pressure in the cylinder 34 and the conduit 5| drops. A similar pressure drop is created in the pressure chamber 93 through its connection to the conduit 5| whereby the compression spring 59 forces the piston 59 towards the'leit until equilibrium is reached. This causes the valve members 35 and 32 .of the mechanisms 33 and 30 respectively to move towards the left and to disconnect successively the inlets and outlets of some of the motors. At first the inlet conduit 29 and the outlet conduit 28 of the motor 24 are disconnected, then the inlet and outlet conduits 28, 29 of the motor 23, and finally the inlet and outlet conduits 28, 29 of the motor 22 are disconnected so that ultimately the conduit 29 of the motor 2| only receives high pressure fluid from thecylinder 34. To prevent disconnecting of the conduits 29 and 28 of the motor 2| from the cylinders 34 and 3| respectively, stops 10 are provided within the cylinders 34 and 3| for engaging the cylindrical members 35 in their lefthand end positions. Thus, with the arrangement described above the number of a plurality of hydraulic motors is automatically varied in response'to variations of torque and speed. As the speed of the motor unit increases all except one of the motors are successively disconnected or placed outof operation. While no operating fluid is supplied to some of the motors, their gears continue to run idle. During this idling condition it is important to prevent locking of {any one of the motors, that is, to assure draining of fluid therefrom and to prevent the building up of excessive pressure due to presence of operating fluid within any one of the motors. This is accomplished by the provision of the special design of the movable valve members 35 of the valve mechanisms 30 and 33 described above. These movable members permit draining of fluid from any motor while idling. Assuming in Fig. 3 fluid under pressure in the conduit 29 were built up, the fluid ,pressure through the port 39 forces the plate 39 ,towards the left against the biasing force of the spring n thus permitting'draining of fluid and preventing the building up of excessive pressure within the conduit 29 in a position in which the cylinder 35 covers completely the port connection to the particular confiuit29. Thus, in the case described, operating fluid may always be discharged through the conduits 29 and the movable valve member 32, particularly also in any position of the valve member 32 in which it covers completely the port connection to any of the conduits 28 of the motors 22, 23 and 24.

If during operation the torque on the shaft 25 is increased, as may occur when a vehicle has to climb a hill, the speed of the output shaft 25 is reduced. This increases the restriction to flow through the motors then in operation and the building up of pressure in" the cylinder 34 and the pressure chamber 53, causing the piston 59.

to move towards the right. This effects similar movement towards the right of the movable valve members 35 of the mechanisms 33 and 30 to connect additional motors in parallel with the motor 2| untir equilibrium is reached between the force created by the pressure in the chamber 63 and the force of the spring 00. g

The righthand end portions of the cylinders 34 and 3| are connected by drain conduits H and 12 to the reservoir It to drain operating fluid discharged from the motors and leaking past the movable valve members 35 into the righthand end portions of the cylinders 34 and 3| respectively. ,Upon reversing of the reversing valve 42 into the position indicated in Fig. 4, the operation of the hydraulic torque transmission arrangement is similar to that described above ber 63 from the conduit I1 through the reversing valve 42 and the conduits i2, 88, and fluid is discharged from the chamber 63 through the conduits 84, SI and the reversing valve 42 through the drain conduit, 69 to the tank l8.

An arrangement according to. my invention adapts itself readily to load changes, it is equally eflective for either direction of rotation, and operates at high eiliciency under varying torque and speed conditions.

The modification shown in Fig. comprises hydraulic pump means 15 corresponding to the pump ID of Fig. 1 and arranged to receive oper ating liquid from a reservoir II. The pump means 15 has a discharge conduit 'I'l'connected through a reversing valve 18 to hydraulic motor means 19 corresponding to the hydraulic motors 20 of Fig. 1 and controlled by valve mechanisms ll, ll actuated by a pressure responsive device or servo motor 82. The arrangement so far described is similar to that shown in Fig. 1. The

hydraulic motor 82 is connected by a pipe 83 tothe discharge side of the hydraulic pump means 15. The pipe 83 is connected to the discharge conduit 11 ahead of the reversing valve 18, thus permitting the elimination of restrictions such as the restrictions 65 and 61 in the-conduits 64 and 66 respectively of Fig. 1 and requiring only a single pipe 83 in place of the two conduits 64, 66 of Fig. 1. The operation of this arrangement otherwise is similar to that of Fig. 1.

What I claim as new and desire to secure by Letters Patent of the United States is:

Hydraulic torque transmission arrangement comprising a gear pump having an inlet conduit for connection to a source or operating liquid and a discharge conduit, a plurality of hydraulic motors each having a first and a secondopening for receiving and discharging fluid, separate control valve mechanisms for connecting in parallel the flrst and second openings respectively, each I control valve mechanism comprising a cylinder having a plurality or axially spaced ports connected to said openings and an exhaust port near one end, a hollow piston member wider than the ports to and from said-openinBs being slidably disposed in the cylinder and having a port in its wall and a bottom, a cover plate and'means yieldably biasing the plate towards closing position against the open end of the piston member to relieve fluid pressure from any motor whose respective port registers with the piston member,

means including a reversing valve for connectingthe pump discharge conduit to either of the control valve mechanisms to operating fluid to the flrst openings and in another position to the second openings, and means including a device for positioning the piston members in response to changes of the pump discharge pressure.

JOHN H. DORAN.

conduct in one position 

